This invention relates to conduits, and in particular, to helically wound flexible conduits and a strip for forming a helically wound conduit.
Helically wound conduits are used for many types of fluid handling in many applications, especially in the field of fume extraction. These conduits may be constructed by helically winding a flexible strip of material to form a helically-wound conduit. Often these conduits are placed in environments which require air or other gases to be transferred around corners. Some environments are enclosures which require a fluid to be transferred from one end of the enclosure to another where an obstacle lies in the direct line path. In other cases, the conduit must pass through a complex path which requires one or more changes of direction.
One solution is to use a series of ducts which are connected to transport the fluid around the obstacle or around the corner. This solution is complex and costly as very exact measurements must be made to ensure that the ducts are properly joined together and that the inlet and outlet are at the desired locations.
Another way to get around this problem is to use a conduit formed from flexible material and bending the conduit around that corner. However, if such a conduit is required to pass through a lengthy passage and is only supported at each end, the conduit will droop in the middle.
Another solution to this problem is to join together a plurality of separate conduits having the necessary shape and stiffness or flexibility. However, such a conduit requires joints to connect the separate conduits resulting in undesirable manufacturing difficulties.
Accordingly, there is a need for a conduit having at least one flexible section and at least one stiff section without reduces the complexity of manufacture by using fewer components.
The present invention is accordingly directed to a strip for forming a helically wound conduit having at least one first elongated strip portion formed from a first material having a first and a second strip end and at least one second elongated strip portion formed from a second material having a first and second strip end. The second strip end of the at least one second strip portion is affixed to the first strip end of the first strip portion to form a single continuous strip. The second material is more flexible that the first material. Preferably, the first strip portion and the second strip portion have the same width.
In a preferred embodiment, the strip also has a reinforcing wire affixed to at least one of the first strip portion and the second strip portion. The strip has a leading edge and a trailing edge and may be wound helically to form a generally cylindrical conduit, the trailing edge being affixed to the leading edge of each successive helix.
This invention is also directed to a continuous elongated strip for forming a helically wound conduit having a plurality of first elongated strip portions formed from a first material and second elongated strip portions formed from a second material. The strip portions each have a first and second strip end. The first and second strip portions are alternately affixed to one another by affixing the first strip ends to the second strip ends to form a single contiguous strip. The second material is more flexible than the first material.
This invention is also directed to a helically wound conduit for conducting fluids. The conduit has at least one first conduit section formed from a helically wound first strip portion formed from a first material. The conduit also has at least one second conduit section formed from a helically wound second strip portion formed from a second material. The second strip portion is affixed to the first conduit section to form a single contiguous conduit. The second material is more flexible than the first material.